1. Technical Field
The present invention relates to a piezoelectric vibration module.
2. Description of the Related Art
In general, in portable electronic apparatuses such as a cellular phone, an electronic book (E-book) terminal, a game machine, a PMP, and the like, a vibration function is used for various purposes.
In particular, a vibration generator for generating vibration is primarily mounted on the portable electronic apparatuses to be used as a warning function which is a silent receiving signal.
Due to implementation of multi-functions of the portable electronic apparatuses, the vibration generator actually requires miniaturization, integration, and various high-functionality at present.
Furthermore, a touch type device has been generally adopted, which performs an input operation by touching the portable electronic apparatus according to a user's request to intend to conveniently use the portable electronic apparatus.
A haptic device which is currently in common use widely includes even a concept of reflecting interface user's intuitive experience and further diversifying a feedback for a touch in addition to a concept of performing an input operation through the touch.
The haptic device generally provides vibration through repeated extension and/or shrinkage as external power is applied to a piezoelectric element. The piezoelectric element can improve moisture-resistance and durability as disclosed in an ultrasonic linear motor of Patent Document 1.
In the ultrasonic linear motor according to Patent Document 1, a protection material, for example, silicon rubber surrounds the circumference of the piezoelectric element to prevent collision with a plurality of constituent members constituting the ultrasonic linear motor so as to improve the life-span thereof as well as the performance of the piezoelectric element under an environment with high humidity or an environment with lots of dust.
However, the ultrasonic linear motor according to Patent Document 1 surrounds the rest of the parts other than a part of the piezoelectric element generating vibration force through translation movement, and as a result, extension or shrinkage deformation rate is remarkably reduced.
That is, the protection material in the related art may still cause the vibration force of the piezoelectric element from deteriorating. Therefore, another measure for protecting the piezoelectric element from external factors should be taken.